From H. C. Sorby 22 March 1876
Broomfield | Sheffield.
March 22/76
My dear Mr. Darwin
I am sorry you should have felt any kind of hesitation in writing to ask my help in any of your researches since at any time I shall be only too glad to do what I can to assist in any experiments that you may think it desirable to make.1 I only wish I could do more than I fear is possible in the case you name. Assuming that the sugar is glucose (i:e: grape sugar) the most delicate test I know is to take an ammoniacal solution of oxide of copper so dilute as to be only just a faint blue and to observe whether it is decolourized by boiling with the suspected substance. I really cannot say how small a quantity of glucose could be detected in this manner, but it must be a very small fraction of a grain—perhaps less than th. Perhaps other tests might be found but it would require considerable research to be sure. Even this is not a certain proof but if no decolourization occurred it would prove that glucose is absent or in very minute quantity. I do not know any very delicate test for cane sugar.2
In order to use the test one ought to have the leaves tolerably fresh and damp. If you like to send some I will try what I can do but will not promise that the results will be satisfactory.
All being well I must leave here for London on April 4th. so you ought to send the leaves as soon as you can.
I inclose a ticket for my conversazione. I should be delighted to see you at it but if you could not come, perhaps one of your sons could. I have therefore filled it up merely Mr. Darwin.3
Yours very truly | H. C. Sorby
I will send you a corrected copy of my address.4 Before you publish any thing on the subject, drop me a line, so that I may let you have the most recent results.
Footnotes
Bibliography
Earthworms: The formation of vegetable mould through the action of worms: with observations on their habits. By Charles Darwin. London: John Murray. 1881.
Sorby, Henry Clifton. 1876. The president’s address. [Read 2 February 1876.] Monthly Microscopical Journal 15: 105–21.
Summary
Discusses chemical tests for the detection of glucose and cane-sugar in solution.
Letter details
- Letter no.
- DCP-LETT-10425
- From
- Henry Clifton Sorby
- To
- Charles Robert Darwin
- Sent from
- Broomfield, Sheffield
- Source of text
- DAR 177: 218
- Physical description
- ALS 4pp
Please cite as
Darwin Correspondence Project, “Letter no. 10425,” accessed on 23 April 2024, https://www.darwinproject.ac.uk/letter/?docId=letters/DCP-LETT-10425.xml
Also published in The Correspondence of Charles Darwin, vol. 24